Method and apparatus for discrimination between different kinds of data transmission
First Claim
1. In the operation of a data communication station comprising a first data terminal operating under a first transmission standard under which an incoming call starts with a preliminary ring signal and a subsequent recognition signal, a second data terminal operating under a second, different transmission standard under which an incoming call starts with a preliminary ring signal and may include a subsequent recognition signal, and selective switching means for connecting a telephone line or like communication line to either of the data terminals for completion of an incoming call that starts with a ring signal, in which station the switching means normally maintains at least one of the data terminals connected to the communication line in on-hook condition prior to initiation of a call, the method of operation, for an incoming call, comprising:
- A. permitting the one data terminal, responsive to a ring signal received on the communication line, to go off-hook;
B. disconnecting the one data terminal from the communication line, by operation of the switching means, without signalling an on-hook condition to the communication line;
C. monitoring the communication line for occurrence of a recognition signal within a given recognition time interval T3; and
D. actuating the switching means to connect only the first data terminal to the communication line, off-hook, to complete the call to the first data terminal, when a recognition signal from the first transmission standard is identified during interval T3 in step C; and
E. actuating the switching means to connect only the second data terminal to the communication line, off-hook, to complete the call to the second data terminal when no recognition signal from the first transmission standard is identified during interval T3 in step C.
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Accused Products
Abstract
A data communication station comprises a first and second data terminals operating under first and second transmission standards, and a selective switching means to connect those terminals to a single communication line; the first data terminal is usually a teleprinter or other character-by-character terminal capable of operating under applicable standards such as those for Economy Telex or for DDD (Direct Distance Dialing) ASCII transmissions, whereas the second data terminal may be a facsimile machine or other graphics terminal operating under the CCITT T-series standards. In one embodiment the switching means is a free-standing control unit that may be connected to virtually any conventional data terminals; in another version the switching means is incorporated in an input/output board in one data terminal and utilizes a part of the logic of that data terminal. The switching means normally maintains the two data terminals connected to the communication line with each in its on-hook condition; in response to the ring signal of an incoming call, both data terminals initially go off-hook. The switching means then disconnects one terminal (usually the facsimile terminal) from the line while maintaining an off-hook condition for the line, and monitors the line for occurrence of a recognition signal for the other terminal in a procedure that connects the line to only one of the data terminals to complete the call, depending on the monitoring function.
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Citations
28 Claims
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1. In the operation of a data communication station comprising a first data terminal operating under a first transmission standard under which an incoming call starts with a preliminary ring signal and a subsequent recognition signal, a second data terminal operating under a second, different transmission standard under which an incoming call starts with a preliminary ring signal and may include a subsequent recognition signal, and selective switching means for connecting a telephone line or like communication line to either of the data terminals for completion of an incoming call that starts with a ring signal, in which station the switching means normally maintains at least one of the data terminals connected to the communication line in on-hook condition prior to initiation of a call, the method of operation, for an incoming call, comprising:
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A. permitting the one data terminal, responsive to a ring signal received on the communication line, to go off-hook; B. disconnecting the one data terminal from the communication line, by operation of the switching means, without signalling an on-hook condition to the communication line; C. monitoring the communication line for occurrence of a recognition signal within a given recognition time interval T3; and D. actuating the switching means to connect only the first data terminal to the communication line, off-hook, to complete the call to the first data terminal, when a recognition signal from the first transmission standard is identified during interval T3 in step C; and E. actuating the switching means to connect only the second data terminal to the communication line, off-hook, to complete the call to the second data terminal when no recognition signal from the first transmission standard is identified during interval T3 in step C. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 28)
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18. A control for selectively switching a telephone line or like communication line to serve both a first data terminal, operating under a first transmission standard under which an incoming call starts with a preliminary ring signal and a subsequent recognition signal, and a second data terminal, operating under a second transmission standard under which an incoming call starts with a preliminary ring signal and a subsequent recognition signal, comprising:
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second terminal relay means for connecting the second terminal to the communication line; a first off-hook detector for determining whether the first terminal is off-hook; a second off-hook detector for determining whether the second terminal is off-hook; recognition timer means, connected to both off-hook detectors, for measuring a predetermined recognition time interval T3, starting from the time at which both terminals go off-hook in response to a ring signal on the communication line; second relay control means, connected to the timer means and to the second terminal relay means, for actuating the second terminal relay means to disconnect the second terminal from the communication line during the interval T3; and monitoring means for monitoring the communication line for occurrence of a recognition signal from the first transmission standard during the interval T3; the second relay control means further being connected to the monitoring means and maintaining the second terminal disconnected from the communication line in response to occurrence of a recognition signal from the first transmission standard during the interval T3. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27)
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Specification